Dental broach.



W. W. FOWLER.

DENTAL BROACH.

APPLICATION FILED SEPT. 24, 1912.

1,067,015. Patented July 8,1913.

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WILLIAM W. FOWLER, OF BIVEBDALE, MARYLAND.

DENTAL BROACH.

specification of Letters Patent.

Patented July 8,1913.

- Application filed September 24, 1912. Serial No. 722,023.

To all whom it may concern.

Be it known that I, WILLIAM W. Fownan, a citizen of the United States, residing at Riverdale, in the county of Prince Georges and State of Maryland, have invented certain new and useful Improvements in Dental Broaches, of which the following is a specification.

" tion hereinafter fully described and claimed,

and as shown in the accompanying drawing, in which Figure 1 is a plan view of the blank from which the broach is made, showing the same at the completion of the first step of manufacture. Fig. 2 is a transverse section on line 2--2, of Fig. 1. Fig. 3 is a plan view of the blank as it appears after the completion of the second step. Fig. 4. is a transverse section on the line 4-4 of Fig. 3. Fig. 5 is a plan view of the blank as it appears after the completion of the third step. Fig. 6 is a transverse section on the line 6-6 of Fig. 5. Fig. 7 is a view of the completed broach. Fig. 8 is an enlarged detail section on the line 8-8 of Fig. 7.

In carrying my invention into practice, I take a piece of round spring-tempered wire of the desired length and gage and shape the butt end 1 in any suitable manner, after which the prong portion 2 is rendered of greater flexibility than the handle or shank portion 3 by tapering said prong portion longitudinally and uniformly toward its pointed extremity 4, as shown. This may be accomplished by grinding or filing the prong portion until it accurately fits within a grooved templet or other gaging device, whereby accuracy in shaping the prong is insured. The blank produced, as above described, and shown in Fig. 1, is then polished and the entering end 4. finally pointed to the'desired degree, after which the acting portion of the prong 2 is flattened, as shown at 5' in Figs. 3 and 4. This acting portion may be made of any longitudinal extent desired, as a result of which the flexibility and transverse dimension of said portion is increased in one direction and curved surfaces 6 left at the longitudinal edges of the fiattened section. These edges 6 are next ground down to substantially plane surfaces 7, forming at their angles of intersection with the remaining sides of the flattened section 5 Ion itudinal cutting or reaming edges 8, as s own in Figs. 5 and 6. The blank thus far prepared is then placed in a suitable chuck or holder and by any suitable means turned 0r rotated to twist the portion 5, as illustrated in Figs. 7 and 8, showing the com leted broach, forming a continuous doub e coil or spiral9 having continuous longitudinal reamng or cutting ed cs 10 and 11 and a terminal entering point 12. These cutting or reaming edges are preferably plane surfaced, in order to revent the waste of material encountered in forming barbs or spurs thereon, whereby the cost of manufacture is increased on account of the number )f defective breaches which must be discarded as unfit for service, but under some conditions the reaming edges may be barbed or spurred to meet trade requirements. r

The broach constructed as above described is rovided with a s irally-coiled portion wh1ch is longitudinal y. tapered and pointed and thus adapted to be readily inserted into a root canal, and which is also provided with cutting ed es adapted to ream the wall of the canal an thus remove all tissue d 11'- ing the rotation of the broach, whereby the nerve will be positively engaged for ext-raction and the canal at the same time thoroughly cleaned. The portion of the rong between the coiled part 9 and the ham le or shank is freely flexible, by reason of its circular and tapered formation, while the flattened twist of the coiled portion gives it a wide amplitude of universal fiexibilit thus allowing the acting portion of the'liroach to be disposed at any required working angle without liability of fracture.

The described construction of the twist or coil 9 produces an extracting and reaming surface which has a screw-like action when the broach is rotated in a clockwise direction, thus adaptin the broach for use in penetrating and ceaning out very small canals without the objectionable pressure required in the use of broaches of ordinary construction. This allows the breach to be fed forward until the end of a canal is infecting the tooth socket.-

l'mnfhed without liability of its becoming, broken oli' within the canal or of being} forced through the canal and entering and By the use of a i1attwist the coiled poi-ion, if it should become bound in a canal, may be twisted upon itself by manipulation of the shank, so that it will, cut itself loose, thnsavoiding all liability-of brea'kagei Moreover, unlike ordinary barbed broaches, "my improved broach instead of engaging only portions of the wall'of the canal will cleanly scrape or roam the canal throughout its (length, insuring.the removal oil/ all substances liable to cause infection or decay. 7

In practice I preferably provide lneai'l of a suitable character for indicating the extent to which the broach may be inserted to reach the end of the root canal of an average tooth, thus enabling a dentist to determine to an approximately accurate degree just how far the breach has been inserted, so 1 that he may work with proper confidence and caution to nevent undue projection of the broach when the indicating means registers with the outer end of the canal or some other suitable portion of the tooth in connet-lion with which the indicating means is employed as a gage. To this end, the upper surface of the broach may be blued or otherv. e rendered of contrasting color or appearance to the lower surface thereof, such as from the butt end 1 to a point 12' on the prong, the distance of which from the entering point 12 will indicate the distance to which the prong may besafely introduced within a root canal of an average length.

Having thus described my invention, I claim:

A spring tempered dental broach comprising handle and prong portions, said prong portion being of circular cross section. atits inner end and flattened to a rectangu lar cross section at its outer end and being tapered longitudinally throughout to a point, said flattened end of tlieprong por- C. C. Harms. 

